Synchronous controls



May 21, 1945 E. c. WAHLBERG SYNCHRONOUS OCONTROLS Filed Sept. 6, 1945 windings through lthe slip rings, as by closing the switch 80v in its lower position, ilxed poles are established in the armature which, in cooperation with the iixed poles normally established lin the separately 'excited lleida, serve to angularly position the armatures with respect to their respective fields, and hence to position them 'electrically with respect to each other. running, the switch 88 is thrown to its upper position so as to supply current to the commutators of the motors in the usual manner. During running, the slip rings still being connected in parallel provide an alternating current circuit between the armatures oi' the motors and cause the motors to run in synchronism, as is also more fully explained in my above-identified application. as well as in my copending application Serial No. 472,464 filed January 15, 1943. The llrst of said copending applications shows a three-phase tie between the armatures, while the second shows a single-phase tie, which latter is the system illustrated in Fig. 2.

Referring again to Fig. l, th'e shaft 82 of motor 82 carries a pinion 54 arranged to rotate the disc I8 of switch I4. The shafts 88 and 88 oi motors 84 and 88 carry pinions 88 and 82, respectively, `which drive racks 84 and 88 arrange to vary the tension on the speeder springs of centrifugal governors 88 and 10. These governors are driven in any suitable manner by the internal combustion engines 12 and 14. As shown, these are the engines of a two-engine aircraft. each engine driving a propeller. The governors are arranged to control the speeds'of the respective engines in any well-known-manner. In an aircraft this control is usually eifected by varying the pitch of the For e blades of variable pitch propellers and such a control is dlagrammatically illustrated in Fig. 1 The governor control per se is well-known and hence a detailed description thereof is not necessary, it being sumcient to state that an increase in the speed of an engine causes its governor to increase thepitch of the associated propeller, thereby increasing the load on the engine and slowing it down in order to maintain the speed for which the governor has been set. Heretofore,

in order to change the speeds of the motors, it has been necessary to individually vary the governor settings and it is practically impossible, particularly during flight, to change the settings of the dinerent governors equally so that all the engines will operate at synchronous speed. It is a chie! object of this invention to provide means enabling the pilot to change the settings of all of the governors by equal selected amounts, thereby maintaining the engines in synchronism at all speeds.

'Ille eld windinss 88, III, and 42 of the electric motors are connected in parallel across th'e conductors 28 and 80 and a normally open contact D: is interposed in conductor 28 ahead of the field windings. The pairs of slip rings 44, 48, and 48 are likewise connected in parallel across the conductors 28 and 88 and in series with the normally closed contacts F; and F4.

Normally open contacts Fa and Fe are interposed as shown in the conductors 28 and 88, respeetively. The armatures 82, 84. and 88 are connected in parallel between conductors 18 and 18. Conductor 'i8 is connected to conductor 28 through the normally open contact B4, and'is connected to the conductor 88 through the normally open contact A.. Conductor 'I8 is connected to the conductor 28 through the normally open contact A4, and to the conductor 88 through th normally open contact Be. The conductors i8 and 'i8 are connected together through the normally closed contacts As and Bs arranged in series.

The above-described device operates as follows:

Itis assumed that the engines 12 and 14 are running and the tensions on the speeder springs of the governors 88 and l0 are properly adjusted so that the engines are maintained at a predetermined synchronous speed. If one of the engines tends to run fast or slow with respect to this speed, its governor, in well-known manner, automatically changes the pitch of the propeller driven by this engine, increasing the pitch if the engine runs fast and decreasing it if the engine runs slow.

If the pilot wishes to change the synchronous speed at which the engines are running, he turns the contact arm 22 of the rotary switch i4 in one direction or the other. It will be assumed that he turns the arm 22 clockwise into contact with segment 20. As will be apparent hereinafter, the angle through which the arm 22 is turned determines the magnitude of the speed change.

Movement of arm 22 into contact with segment 20 energizes solenoid A, thus closing contacts A1, Az, A4, and As, and opening contacts As and As. Closing of contact A2 energizes solenoid D, inasmuch' as contact C1 is normally closed, and consequently contacts D1, Dn, and D: are closed. Closing of D1 provides a holding circuit for relay D as long as Cris closed, and closing of D2 does not heat thermal relay C inasmuch as contact AJ was opened .by the energization of solenoid A. The closing of D: supplies current from the conductors'28 and 38 for excitingathe fields 38, 48, and 42. l

Inasmuch as contacts F1 and F4 are normally closed, current is also supplied to the pairs of slip rings 44, 48, and 48, and the armatures of motors 82, 84, and 88 are turned into the same angular positions with respect to their stationary fields and hence with respect to each other, as previously described. Ordinarily, if the systemhas been operating, the armatures will be in such positions,

but particularly when the system is first placed in operation, one or more of the armatures may be a fraction of a turn out of proper position, and it is important that th'ey be correctly positioned in order that they may start and run under load in perfect synchronism. t,

Closing of contact A: also completes the circuit through the heating coil of thermal relay E, inasmuch as contact Fn is normally closed, but the resultant closing of contact El is delayed a sumcient interval for the above-described positioning to take place. When E1 does close, solenoid F is energized, because contact Aihas been closed. with the result that contacts F1, Fs, and Fa are closed, and contacts Fn, Fs, and F4 are opened. Closing of F1 provides a holding circuit around contact Ei for solenoid F, while opening of Fn drops out thermal relay E. Opening of Fa and F4 interrupts the supply of direct current to the slip rings 44, 48, and 48, and closing of Fs and Fu supplies current to the commutators of motors 82, 84, and 88 through the already closed contacts A4 and Aa, th'e contact As having been opened to thus remove a short circuit. Although the contacts Fa and F4 are open, the slip rings of the motors are still connected together in parallel, and consequently the motors start` and run in synchronism.

Rotation of motors 84 and 88 causes the pinions 88 and 82 to drive the racks 84 and 88 in synchronism so as to change by equal amounts the ten' sions of the speeder springs of the respective governors. If turning of the contact arm 22into contact with segment v20 causes the motor to rotate in .a direction which moves the racks to the right, as viewed in Fig. 1, this increases the tension. The engines 12 and 14 are hence run-v ning too slow for the new setting of the governors, and consequently the governors decrease the pitch of the respective `propellers tothus reduce the loads on the engines, which permits the engines to come up to the desiredspeed.

At the same time, the motor 32, operating in synchronism with motors 34 and 26, is driving the disc I6 in a clockwise direction. Inasmuch as the contact arm 22 remains stationary, this rotation of the disc moves segmentsZU and I8 until the insulated space between them comes into alignment with the arm, thus interrupting the circuit through the solenoid A. It will thus be seen that the farther arm 22 was originally moved, the longer it will take motor 32 to rotate the disc to its neutral or off position with respect to the arm 22, and consequently the longer the motors 34 and 36 will drive the racks B4 and 68, and hence the greater will be the change in engine speed eilected thereby. Conveniently, suitable calibrations may be provided to indicate how far. the arm 22 must be moved to eilect a desired change in engine speed.

When the disc is rotated to de-energize the.

solenoid A, in the manner just described, the contacts A1, A2, A4, and Ae are opened; and the contacts A3 and A5 are closed. Opening of A4 and A6 interrupts the supply of current to the coinmutators of the motors 32, 34, and, while the closing of A short circuits the armatures to prof vide dynamic braking, thus stopping the motors quickly. Y

Opening of contact A1 de-energized solenoid F thus opening contacts F1, F5, and Fe and closing contact with segment I8, thus energizing solenoid B. The same sequences taire place as occurred when solenoid A was energized, except that the contacts A1, A2, Aa, A4, A5, and Ae remain as they are shown in Fig. l, while contacts B1, Bz, B4, and Be are closed, and contacts B3 and B5 are opened. The result of this is the saine, except that the closing of B4 and Bc reverses the polarity of the armatures of motors 32, 34%, and with respect to what it was when A4 and A@ were closed, and consequently the motors operate in the opposite direction. Motor 352 drives the disc i@ in a counterclockwise direction so as to bring the contacts IE and 2d into their neutral position with respect to the arm 22, and the motors all and 36 drive' the racks 64 and Gato the left, as viewed in Fig. 1, so as to reducer the tension of the Speeder springs in the governors 68 and 10. vThe governors are hence set to maintaina lower engine speed, and inasmuch as the engines are now running too fast with respect to this new setting, the governors increase the pitch of the respective propellers so as to slow down the engines.

When the disc i6 has been rotated a suiiicient distance to open the circuit through solenoid B, the motors are dynamically braked and positioned in the same manner as above described.

Inasmuch as the motors always start, run, and stop in absolute synchronism, the changes in the settings of the several governors are alwaysl the same. Moreover, all the pilot has to do in order contacts F2, F3, and F4. The. closing of contacts F3 and F4 applies direct current to the slip rings 44, 46, and 48, inasmuch as contact Da is still closed, and the field windings 38, 40, and 42 remain excited and hence the armatures of the motors.' which are quickly decelerated by the dynamic braking, as above described, are stopped in the same positions relative to their stationary fields and consequently relative to each other. The closing of F2 supplies current through contact D1, which is still closed, to the heating coil E, but the subsequent closing of E1 has no effect, as both contacts A1 and B1 are open.

Closing of contact A3 causes current to ilow through the heating coil C inasmuch as contact B3 has not been opened and contact D2 is still closed. After a predetermined interval, which is sufficiently long for the above-described stopping and positioning of the armatures to take place, contact C1 is opened, thus de-energizing solenoid D. This opens contacts D1, D2, and D3.'

Opening of D2 cuts off the flow of current to the heating coil C, while opening of D3 interrupts to change the speed of the engines is to turn the arm 22 .to the proper point on one orthe other Aof the scales on disc i6, which gives him the increase or decrease in speed desired. Thereafter, the system is fully automatic and requires no further attention on the part of the pilot until he again wishes to change the speed of the engines.

' plurality of electric motors synchronous throughout starting, running, and stopping connected to be controlled by said circuit, and switching mech-l anism having movable means for closing said cir' cuit to energize said motors, one of said motors .being drivingly connected to said switching mechanism and operative to open said circuit to deenergize said motors, said switching mechanism being so arranged that the distance said movable means is moved determines the extent of motor operation required to open said circuit.

2. In. an electric system, a plurality of electric motors synchronous' throughout starting, running, and stopping, and switching mechanism having means movable in one direction to energize said motors for forward rotation and mov- 1 able in the other direction to energize said motors for reverse rotation, one of said motors being drivingly connected to said switching mechanism for operating the latter to stop said motors, said switchingl mechanism being so arranged that the distance the movable means is moved determines the extent of motor operation required to operate said mechanism to stop the motors.

3. In an electric system, a plurality of electric motors, an electric circuit, switching mechanism having movable means for closing said circuit,`

means responsive to the closing of said circuit for positioning-the armatures of said 'motors with While I have shown and described a more orv `less specific embodiment of my invention, it isA 'cuit for stopping said motors, said switching mechanism being so arranged that the distance said movable means is moved determines the extent of motor operationgrequired to open said circuit.

4. In an electric system, a plurality of electric motors, an electric circuit, switching mechanism having movable means for closing said circuit, means operative by the closing of said circuit for causing said motors to operate in synchronism, one of said motors being drivingly connected to said switching mechanism and operative to open said circuit, and means responsive to the opening of said circuit for stOPDill said motors and for positioning the armatures thereof with respect to their fields, said switching mechanism being so arranged that the distance said movable means is moved determines the extent of motor operation required to open said circuit.

5. In an electric system, a plurality of electric motors, an electric circuit, switching mechanism having movable means for closing said circuit, means operative by the closing of said circuit for causing said motors to operate in synchronism, one of said motors being drlvingly connected to said switching mechanism and operative to open said circuit, and'means responsive to the opening of said circuit for dynamically braking said motors and i'or positioning the armatures thereof with respect to their fields, said switching mechanism being so arranged that the distance said movable means is moved determines the extent of motor operation required to open said circuit.

6. In an electric system, a plurality of electric motors, an electric circuit, switching mechanism having movable meansl for closing said circuit, means responsive to the closing of said circuit for positioning the armatures of said motors with respect to their fields, means operative after said armatures have been positioned to cause said motor to start and run in synchronism, one of said motors being drivingly connected to said switching mechanism and operative to open said circuit, and means responsive to the opening of said circuit for stopping said motors, and for positioning ythe armatures thereof with respect to their fields, said switching mechanism being so arranged that the distance said movable means is moved determines the extent of motor operation required to open said circuit.

7. In an electric system. a plurality of electric motors,v two electric circuits, switching mechanism having means movable in one direction to close one oi' said circuits and movable in the other direction to close the other of said circuits. means responsive to closing of said one circuit for positioning the armatures of said motors with respect to their fields and means operative thereafter for causing said motors to start and run in 4cuit has been closed by the movable means, and

means responsive to the opening of either of said circuits for stopping said motors, said switching mechanism being yso arranged that the distance said movable means is moved determines the extent of motor operation in the respective direction required to open the respective circuit.

8. In Ian electric system, a plurality oi electric motors, two electric circuits, switching mechanism having means movable in one direction to close one oi' said circuits and movable in the other direction to close the other of said circuits, means responsive to closing of said one circuit for positioning the armatures of said motors with respect to their ilelds and means operative thereafter for causing said motore,l to start and run in synchronism in a forward direction, means responsive to closing of said other circuit for positioning the armatures of said motors with respect to their fields and means operative thereafter for causing said motors to start and run in synchronism in a reverse direction, one of said motors being drivingly connected to said switching mechanism and operative to open whichever circuit has been closed by the movable means, and means responsive to thel opening of either of said circuits for stopping said motors and positioning their arma.- tures with respect to` their elds, said switching mechanism being so arranged that the distance said movable means is moved determines the ex- .tent ofl motor operation in the respective direction required to open the respective circuit.

9. In an electric system, a plurality of electric motors, two electric circuits, switching mechanism having means movable in one directionto close one o! said circuits and movable in the other direction to close the other of said circuits, means responsive to closing of said one circuit for causing said motors to operate in synchronism in a forward direction, means responsive to closing of said'other circuit for causing said motors to operate in synchronism in a reverse direction, one of said motors being drivingly connected to said switching mechanism and operative to open whichever circuit has been closed by the movable means, and means responsive to the opening of either of said circuits for dynamically braking said motors and positioning their armatures with respect to their fields, said switchinglmechanism being so arranged that the distance said movable means is moved determines the extent of motor operation in the respective direction required to open the respective circuit.

I 10. A plurality oi' electric motors having fields and wound armatures, a pair of similarly located taps connected to each armature, conductors for connecting the taps of the different armatures in parallel, an electric circuit, switching mechanism including movable means for closing said circuit,

l relay means responsive to the closing of said circuit for applying direct current to said conductors to thereby position the armature of each motor with respect to .its iield, time delay relay means operative by the closing of said circuit to subsequently interrupt the supply of current to said conductors and to supply current to cause said motors to run, one of said motors :being drivingly connected to said switching mechanism and operative to open said circuit. and relay means operative by the opening of said circuit for stopping said motors, said switching mechanism being so arranged that the distance said movable means is moved determines the extent of the motor operation required 'to reopen said circuit.

11. lA plurality oi electric motors having fields and wound armatures, a pair of similarly located Il taps connected to each armature, conductors for aecomo nected to said switching mechanism and oper-` ative to open said circuit, and relay means operative by the opening of said circuit lfor interrupting said supply of currentand for supplying current to said conductors to thereby position the amature of each motor with respect to its held, said switching mechanism being so arranged that the distance said movable means is moved determines the extent of the motor operation required to reopen said circuit. A

' 12e A plurality of electric, motors having fields and wound armatures; a pair of similarly located taps connected to each armature, conductors for connecting the 'taps of the different armatures in parallel, an electric circuit, switching mechanism including movable means for closing said circuit. relay means responsive to the closing of said circuit for supplying current to cause said motors to run, one of said motors being drivingly connected to said switching mechanism and operative to open said circuit, and relay means operative bythe opening of said circuit for interrupting said supply of current, for short circuiting said armatures to thereby dynamically brake said motors, and for supplying current to said conductors to thereby position the armature of each motor with respect to 'its eld, said switching mechanism being soy arranged that the distance said movable means is moved determines the extent of the motor operation required to reopen said circuit.

interrupt the supply oi.' current to said conductors and to supply current to said commutators to cause said motors to run, one of motors 'being drivingiy connected to said switching mechanism and operative to open said circuit, relay means operative by the opening of said circuit for interrupting the supply oi current to said commutators and for again'supplying current to said conductors for positioning said karmatures with respect to the fields, and time delay relay means operative by the opening ofl said circuit for subsequently interrupting the supply of current to said conductors and. interrupting theexcitation current, said switching mechanism being so arranged that the distance said movable means is moved determines the extent of the motor operation required to reopen said circuit.

15. A plurality of direct current electric motors having fields, wound armatures and commutators, a pair of similarly located-taps connected to each armature, conductors for connecting the taps-oi the diilerent armatures in parallel, two electric circuits, switching mechanism including means movable in-one direction for closing one of said circuits and movable in the other direction for closing the other of said circuits, a commutator circuit, relay means responsive to the closing of one of said circuits for connecting said commu- -tators to said commutator circuit with lone polarity with respect to their iieldsrelay means responsive to the closing ofthe other circuit for connecting said commutatore-to said commutator circuit with a reversed polarity with respect to their fields, relay means responsive tothe closing 13. A plurality or electric motors having neids and wound armatures, a pair of similarly located taps connected to each armature, conductors for. connecting the taps of the different armatures in parallel, an electric circuit, switching mechanism including movablemeans for closing said circuit, relay means responsive to the closing of said circuit for applying direct current to said conductors to thereby position the armature of each motor with respect to its field, time delay relay means operative by the closing of said circuit to subsequently interrupt the supply of current to said conductors and to supply current to cause said motors to run. one of said motors being drivingly connected to said switching mechanism and operof either'of said circuits for supplyingexcitation current to said lfields and for supplying direct current to said conductors to thereby position the armature of each motor with respect to its iield, time delay relay means responsive to the closing of either of said circuits for subsequently interrupting the supply of current to said conductors ative to open said circuit, and relay means operative by the opening of said circuit for interrupting the last-mentioned supply of current and for again supplying current to said conductors to thereby position the armature of each motor with respect -to its field when the motors have stopped, said switching mechanism being so arranged that the distance said movable means is moved determines the extent of the motor operation. required ,A

to reopen said circuit.

14. A plurality of direct current electric motors having fields, wound armatures and commutatore, a pair of similarly located taps connected to each armature, conductors for connecting the taps oi the different armatures in parallel, an electric circuit, switching; mechanism including movable means for closing said circuit, relay means re sponsive to, the closing of said circuit for supply-xl ing excitation current to said fields and for supm plying direct currentto said conductors to there.

by position the armature of each motor with ren spect to its iield. time delay relay means oper ative by the closing of said circuit to'subsequently and for supplying current to said commutator circuit, .one of said motors being drivinly connected to said switching mechanism and-operative to openwhichever of said circuits has been closed, and relay means responsive to the opening of either of said circuits for interrupting the supl ply of current to said commutator circuit and for interrupting said excitation current, said switching mechanism being so arranged that the distance the movable means is moved determines the extent of the motor operation required to reopen said circuit.

i6. A plurality of direct current electric motors having ilelds, Wound armatures and commutators, 'a pair of similarly located taps connected to each armature, conductors for connecting the taps oi. the different armatures in parallel, two electric circuits, switching mechanism including means movable in one direction for closing one of said circuits and movable in the other direction for closing the other of said circuits, a commutator circuit, relay means responsive to the closing of one of said circuits for connecting said commutatore to said commutator circuit with one polarity with respect to their elds, relay means responsive to the closing of the other circuit for connecting' said commutatore to said commutator circuit with a reversed polarity with respect to their iiclds, relay means responsive to the closing of either of said circuits for supplying excitation current to said iields and for supplying direct current to said conductors to thereby position the armature of each motor with respect to its ileld, time delay relay means responsive to the closing oi either oi said circuits for subsequently interruptlng the supply of current to said conductors and i or supplying current to said commutator cir cuit. one of said motors being drivingly connected to said switching mechanism and operative to open whichever of said circuits has been closed, relay means responsive to the opening of either of said circuits for interrupting the supply o! current to said commutator circuit and for supplying current to said conductors to thereby position the amature of each motor with respect to its neld, and time delay relay means responsive to the opening of either circuit for subsequently interrupting the supply of current to said conductors and for interrupting said excitation current, said switching mechanism being so arranged that the distance the movable means is moved determines the citent o! the motor operation required to reopen said circuit.

17. A plurality of electric motors each having a rotor winding and a stator winding, lines to be dition of the nrst relay and to energize the motors from the power lines to cause the motors 'to run in synchronism, means responsive to the opening of the switch to de-energize the first relay and to change the mode of energization of one o! the windings of each oi' the motors from the power lines to cause the motors to synchronously decelerate and to come to rest with their rotors in like positions, a time delay relay which is energized when the second relay is energized and the first p relay is de-energized for de-energizing the second connected to a source ot power, a switch, means responsive to closure of the switch to energize a ilrst relay, means actuated when the nrst relay is energized to energize from the power lines both o! the windings of each oi the motors to position each oi! the rotors with respect to its stator. a time delay relay energized when the nrst relay is energized .to cause a second relay to be energized, means actuated when the second relay is energized to keep the second relay energized regardless of the condition of the time delay relay and to de-encrgize the time delay relay and to change theimode of energization of one o! the windings of each of the motors from the power lines to cause the motors to run in synchronism, and means responsive to the opening of the switch to de-energize both of the windings of each of the motors and to de-energize the first and second relays.

relay, and means actuated when the second relay is de-energized to de-energize both the windings of each of the motors and to ie-energize the time delay relay.

19. A plurality or electric motors each having a rotor winding and a stator winding, lines to be connected to a source of power, a. switch, means Ycondition of the rst relay and to energize from the power lines both o! the windings oi-each of the motors to position each of the rotors in like relative positions, a time delay relay energized when the iirst relay is energized to cause a third relay to be energized, means actuated when the third relay is energized to keep the third relay energized regardless of the condition of the time delay relay and to deenergize the time delay relay and to change the mode of energization of one oi the windings of each oi the motors to cause the motors to run in synchronism, means responsive to the opening oi. the switch to deenergize the first and third relays and to change the mode o! energizationoi the one winding of each ofthe 18. A plurality oi.' electric motors each having a y motors to cause the motors to synchronously decelerate and to come to rest with their rotors in like relative positions, a second time delay relay which is energized when the second relay is energized and the first relay is deenergized ior deenergizing the second relay, and means actuated when the second relay is deenergized to deenergize both the windings oi each of the motors and to deenergize the second time delay relay.

ERIC C. WAHLBERG. 

